GLOBAL MARKETS-Euro and oil resume fall; stocks slip on weak data

* With ECB chief ready to act, euro brushes against $1.20* Crude prices fall in volatile session* Stocks pressured by weak manufacturing readings(Updates prices, adds comment)By Rodrigo CamposNEW YORK, Jan 2 (Reuters) - The euro fell on Friday, continuing the slide that saw the currency finish out 2014 at a 29-month low against the U.S. dollar, on expectations that the European Central Bank will s